The probability of an event is how likely it isto occur. Is a number between 0 and 1. Probability of 1: event is certain to occur. Probability of 0: event will never occur. Probability of ½: equally likely to occur or not.
When all outcomes are equally likely, thetheoretical probability that an event A willoccur is: Can be expressed as a fraction, decimal, or %.
You roll a six-sided die with sides numbered1 through 6. Find the probability of: rolling a 4. rolling an odd #. rolling a # less than 7.
A spinner has 8 equal-size sectionsnumbered 1 though 8. Find the probabilityof: spinning a 6. spinning a # greater than 5.
You put a CD that has 8 songs in your CDplayer and set it to random. The player playsall 8 songs without repeating any song. What is the probability all songs are played inthe same order listed on the CD? What is the probability that 2 of your 4favorite songs are played first, in any order?
There are 9 students on the math team. Youdraw their names one at a time to determinetheir order at the competition. What is the probability that 3 of the 5 seniorson the team will be chosen last?
Five cards are drawn from a 52-card deck.What is the probability that the first two cardsare red?
It is not always possible to find theoreticalprobability. Can sometimes find the experimentalprobability using an experiment, survey, orhistory of the event.
In 1998, a survey asked internet users fortheir ages. Find the exp. probability that arandomly selected internet user is: at most 20 years old? at least 41 years old?Age # of usersUnder 21 163621 -40 661741 – 60 369361 – 80 491Over 80 6
Found by calculating the ratio of two lengths,areas, or volumes. Example: Find the probability that a randomly throwndart would hit the shaded region.4
You have a 2 hour movie recorded at thebeginning of a tape that holds 6 hours ofrecordings. Your brother randomly records a30 minute show on the tape. What is theprobability that his show records over part ofyour movie?
A store is open from 8 am to 8 pm. Themanager works 9-4. What is the probabilitythat the manager is there during a randomcustomer’s 15 minute visit?
The target for a bean-bag toss game is arectangle 3 ft wide and 4 ft tall with 3 circularholes, each with radius 1 foot. What is theprobability that a random bean-bag will passthrough one of the holes?